Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative coo...Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative cooling and solar heating for the uptake of CO_(2) on commercial activated carbons(CACs).During adsorption,the adsorbents are coated with a layer of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene)[P(VdF-HFP)HP],which cools the adsorbents to a low temperature under sunlight through radiative cooling.For desorption,CACs with broad absorption of the solar spectrum are exposed to light irradiation for heating.The heating and cooling processes are completely driven by solar energy.Adsorption tests under mimicked sunlight using the CACs show that the performance of this system is comparable to that of the traditional ones.Furthermore,under real sunlight irradiation,the adsorption capacity of the CACs can be well maintained after multiple cycles.The present work may inspire the development of new temperature swing procedures with little energy consumption.展开更多
In spite of its intrinsic complexities,the passive gait of bipedal robots on a sloping ramp is a subject of interest for numerous researchers.What distinguishes the present research from similar works is the considera...In spite of its intrinsic complexities,the passive gait of bipedal robots on a sloping ramp is a subject of interest for numerous researchers.What distinguishes the present research from similar works is the consideration of flexibility in the constituent links of this type of robotic systems.This is not a far-fetched assumption because in the transient(impact)phase,due to the impulsive forces which are applied to the system,the likelihood of exciting the vibration modes increases considerably.Moreover,the human leg bones that are involved in walking are supported by viscoelastic muscles and ligaments.Therefore,for achieving more exact results,it is essential to model the robot links with viscoelastic properties.To this end,the Gibbs-Appell formulation and Newton's kinematic impact law are used to derive the most general form of the system's dynamic equations in the swing and transient phases of motion.The most important issue in the passive walking motion of bipedal robots is the determination of the initial robot configuration with which the system could accomplish a periodic and stable gait solely under the effect of gravitational force.The extremely unstable nature of the system studied in this paper and the vibrations caused by the impulsive forces induced by the impact of robot feet with the inclined surface are some of the very serious challenges encountered for achieving the above-mentioned goal.To overcome such challenges,an innovative method that uses a combination of the linearized equations of motion in the swing phase and the algebraic motion equations in the transition phase is presented in this paper to obtain an eigenvalue problem.By solving this problem,the suitable initial conditions that are necessary for the passive gait of this bipedal robot on a sloping surface are determined.The effects of the characteristic parameters of elastic links including the modulus of elasticity and the Kelvin-Voigt coefficient on the walking stability of this type of robotic systems are also studied.The findings of this parametric study reveal that the increase in the Kelvin-Voigt coefficient enhances the stability of the robotic system,while the increase in the modulus of elasticity has an opposite effect.展开更多
In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperatur...In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.展开更多
Offshore cranes are widely applied to transfer largescale cargoes and it is challenging to develop effective control for them with sea wave disturbances. However, most existing controllers can only yield ultimate unif...Offshore cranes are widely applied to transfer largescale cargoes and it is challenging to develop effective control for them with sea wave disturbances. However, most existing controllers can only yield ultimate uniform boundedness or asymptotical stability results for the system's equilibrium point, and the state variables' convergence time cannot be theoretically guaranteed. To address these problems, a nonlinear sliding mode-based controller is suggested to accurately drive the boom/rope to their desired positions. Simultaneously, payload swing can be eliminated rapidly with sea waves. As we know, this paper firstly presents a controller by introducing error-related bounded functions into a sliding surface, which can realize boom/rope positioning within a finite time, and both controller design and analysis based on the nonlinear dynamics are implemented without any linearization manipulations. Moreover, the stability analysis is theoretically ensured with the Lyapunov method. Finally, we employ some experiments to validate the effectiveness of the proposed controller.展开更多
基于自适应的延时与丢帧补偿,提出了一种分布式容错策略,用以确保基于CAN(controller area network)总线的混合动力挖掘机电动回转系统在通信出错时获得良好的运行性能。通过采用一种分别在中央控制器和电机驱动器上对反馈信号和控制信...基于自适应的延时与丢帧补偿,提出了一种分布式容错策略,用以确保基于CAN(controller area network)总线的混合动力挖掘机电动回转系统在通信出错时获得良好的运行性能。通过采用一种分别在中央控制器和电机驱动器上对反馈信号和控制信号进行补偿的全新延时补偿方法,可以在不增加通信带宽的情况下大大降低通信错误的不利影响。采用了带遗忘因子的递推最小二乘法对由姿态变化引起的时变模型参数进行辨识,并通过在连续丢帧情况下的反馈补偿中引入反向修正率来消除模型误差的不利影响。仿真和实验结果表明提出的容错策略可以有效第减小通信错误引起的系统超调和响应时间变化。展开更多
An integrated vacuum pressure swing adsorption(VPSA) and Rectisol process is proposed for CO_(2) capture from underground coal gasification(UCG) syngas. A ten-bed VPSA process with silica gel adsorbent is firstly desi...An integrated vacuum pressure swing adsorption(VPSA) and Rectisol process is proposed for CO_(2) capture from underground coal gasification(UCG) syngas. A ten-bed VPSA process with silica gel adsorbent is firstly designed to pre-separate and capture 74.57% CO_(2) with a CO_(2) purity of 98.35% from UCG syngas(CH_(4)/CO/CO_(2)/H_(2)/N_(2)= 30.77%/6.15%/44.10%/18.46%/0.52%, mole fraction, from Shaar Lake Mine Field,Xinjiang Province, China) with a feed pressure of 3.5 MPa. Subsequently, the Rectisol process is constructed to furtherly remove and capture the residual CO_(2)remained in light product gas from the VPSA process using cryogenic methanol(233.15 K, 100%(mass)) as absorbent. A final purified gas with CO_(2) concentration lower than 3% and a regenerated CO_(2) product with CO_(2) purity higher than 95% were achieved by using the Rectisol process. Comparisons indicate that the energy consumption is deceased from 2.143 MJ·kg^(-1) of the single Rectisol process to 1.008 MJ·kg^(-1) of the integrated VPSA & Rectisol process, which demonstrated that the deployed VPSA was an energy conservation process for CO_(2) capture from UCG syngas. Additionally, the high-value gas(e.g., CH_(4)) loss can be decreased and the effects of key operating parameters on the process performances were detailed.展开更多
In order to improve the design of PSA system for fuel cell hydrogen production,a non-isothermal model of eight-bed PSA hydrogen process with five-component(H_(2)/N_(2)/CH_(4)/CO/CO_(2)=74.59%/0.01%/4.2%/2.5%/18.7%(vol...In order to improve the design of PSA system for fuel cell hydrogen production,a non-isothermal model of eight-bed PSA hydrogen process with five-component(H_(2)/N_(2)/CH_(4)/CO/CO_(2)=74.59%/0.01%/4.2%/2.5%/18.7%(vol))four-stage pressure equalization was developed in this article.The model adopts a composite adsorption bed of activated carbon and zeolite 5 A.In this article,pressure variation,temperature field and separation performance are stimulated,and also effect of providing purge(PP)differential pressure and the ratio of activated carbon to zeolite 5 A on separation performance in the process of producing industrial hydrogen(CO content in hydrogen is 10μl·L^(-1))and fuel cell hydrogen(CO content is 0.2μl·L^(-1))are compared.The results show that Run 3,when the CO content in hydrogen is 10μl·L^(-1),the hydrogen recovery is 89.8%,and the average flow rate of feed gas is 0.529 mol·s^(-1);When the CO content in hydrogen is 0.2μl·L^(-1),the hydrogen recovery is 85.2%,and the average flow rate of feed gas is 0.43 mol·s^(-1).With the increase of PP differential pressure,hydrogen recovery first increases and then decreases,reaching the maximum when PP differential pressure is 0.263 MPa;With the decrease of the ratio of activated carbon to zeolite 5 A,the hydrogen recovery increases gradually.When the CO content in hydrogen is 0.2μl·L^(-1) the hydrogen recovery increases more obviously,from 83.96%to 86.37%,until the ratio of activated carbon to zeolite 5 A decreases to 1.At the end of PP step,no large amount of CO_(2) in gas or solid phase enters the zeolite 5 A adsorption bed,while when the CO content in hydrogen is 10μl·L^(-1),and the ratio of carbon to zeolite 5 A is less than 1.4,more CO_(2) will enter the zeolite 5 A bed.展开更多
Consciousness is the gene of resistance that drives evolution by the evolutionary method-empathic Qualia, the subjective perturbation of “natural selection”, and the choice of which is not limited but stress-resista...Consciousness is the gene of resistance that drives evolution by the evolutionary method-empathic Qualia, the subjective perturbation of “natural selection”, and the choice of which is not limited but stress-resistant to mistakes. Looking into the mirror of ourselves, we bring evolution itself to the mirror, which, without blinking, looks with the eye of a frightened gazelle-incredulously-temptingly. Swinging it with a blow to a blow, taking a lunge and reflecting as the shine of slided comet, translating outrage into joy, the most closed resonant system-consciousness works. It is important not to miss any “punch”(knock/sound/word) that is thrown into your consciousness, so that the sound of the universe (and it is she who sends impulses of understanding) turns into improvisation of your own thinking-becoming a landing from “personal Idaho state”, so that the “muscles” of consciousness pumping iron-training do not sleep like a big earthworm that digested fast food (alimentary, cultured), being content with very little and chafing to empty, in order to work, interpreting what is happening near and around you, and comprehend creatively. The cohesion of eidos is so great that thought literally gains weight-you not only get tired quickly in the process of any “thinking”, but you feel that literally the world with weights hangs in your pockets, throwing a couple of blocks with houses and household on your shoulders. And this is all a consequence of the cohesion and microcoupling of all perceptions that revolve in your mind, touching them democratically: with fluids, resonating with waves of meanings, retransmitting impulses of images, and swaddling with the resulting introjections as by current-already according to Maxwell. Let us leave the God of God, art-skillful, and consciousness-seesaw swing of meanings.展开更多
In 2022,the role of digital economy as a stabilizer and accelerator of the national economy was more prominent.Industry digitalization,which is driven by China’ s intelligent manufacturing,has become the main engine ...In 2022,the role of digital economy as a stabilizer and accelerator of the national economy was more prominent.Industry digitalization,which is driven by China’ s intelligent manufacturing,has become the main engine of China’ s digital economy development.As the core component of industrial digitalization,industrial e-commerce also developed in full swing.In the past three years,the COVID-19 pandemic has brought plenty of pressure to China’s industrial economy.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars(22125804)the National Natural Science Foundation of China(21808110,22078155,and 21878149).
文摘Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative cooling and solar heating for the uptake of CO_(2) on commercial activated carbons(CACs).During adsorption,the adsorbents are coated with a layer of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene)[P(VdF-HFP)HP],which cools the adsorbents to a low temperature under sunlight through radiative cooling.For desorption,CACs with broad absorption of the solar spectrum are exposed to light irradiation for heating.The heating and cooling processes are completely driven by solar energy.Adsorption tests under mimicked sunlight using the CACs show that the performance of this system is comparable to that of the traditional ones.Furthermore,under real sunlight irradiation,the adsorption capacity of the CACs can be well maintained after multiple cycles.The present work may inspire the development of new temperature swing procedures with little energy consumption.
文摘In spite of its intrinsic complexities,the passive gait of bipedal robots on a sloping ramp is a subject of interest for numerous researchers.What distinguishes the present research from similar works is the consideration of flexibility in the constituent links of this type of robotic systems.This is not a far-fetched assumption because in the transient(impact)phase,due to the impulsive forces which are applied to the system,the likelihood of exciting the vibration modes increases considerably.Moreover,the human leg bones that are involved in walking are supported by viscoelastic muscles and ligaments.Therefore,for achieving more exact results,it is essential to model the robot links with viscoelastic properties.To this end,the Gibbs-Appell formulation and Newton's kinematic impact law are used to derive the most general form of the system's dynamic equations in the swing and transient phases of motion.The most important issue in the passive walking motion of bipedal robots is the determination of the initial robot configuration with which the system could accomplish a periodic and stable gait solely under the effect of gravitational force.The extremely unstable nature of the system studied in this paper and the vibrations caused by the impulsive forces induced by the impact of robot feet with the inclined surface are some of the very serious challenges encountered for achieving the above-mentioned goal.To overcome such challenges,an innovative method that uses a combination of the linearized equations of motion in the swing phase and the algebraic motion equations in the transition phase is presented in this paper to obtain an eigenvalue problem.By solving this problem,the suitable initial conditions that are necessary for the passive gait of this bipedal robot on a sloping surface are determined.The effects of the characteristic parameters of elastic links including the modulus of elasticity and the Kelvin-Voigt coefficient on the walking stability of this type of robotic systems are also studied.The findings of this parametric study reveal that the increase in the Kelvin-Voigt coefficient enhances the stability of the robotic system,while the increase in the modulus of elasticity has an opposite effect.
基金supported by the National Natural Science Foundation of China(No.62271109)。
文摘In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.
基金supported by the National Key Research and Development Program of China(2018YFB1309000)the National Natural Science Foundation of China(61873134,U1706228)+1 种基金the Young Elite Scientists Sponsorship Program by Tianjin(TJSQNTJ-2017-02)the Tianjin Research Innovation Project for Postgraduate Students(2019YJSB070)。
文摘Offshore cranes are widely applied to transfer largescale cargoes and it is challenging to develop effective control for them with sea wave disturbances. However, most existing controllers can only yield ultimate uniform boundedness or asymptotical stability results for the system's equilibrium point, and the state variables' convergence time cannot be theoretically guaranteed. To address these problems, a nonlinear sliding mode-based controller is suggested to accurately drive the boom/rope to their desired positions. Simultaneously, payload swing can be eliminated rapidly with sea waves. As we know, this paper firstly presents a controller by introducing error-related bounded functions into a sliding surface, which can realize boom/rope positioning within a finite time, and both controller design and analysis based on the nonlinear dynamics are implemented without any linearization manipulations. Moreover, the stability analysis is theoretically ensured with the Lyapunov method. Finally, we employ some experiments to validate the effectiveness of the proposed controller.
基金the National Natural Science Foundation of China (Nos. 51475414, 51475422, and 51521064) and the National Basic Research Program (973) of China (No. 2013CB035405)
文摘基于自适应的延时与丢帧补偿,提出了一种分布式容错策略,用以确保基于CAN(controller area network)总线的混合动力挖掘机电动回转系统在通信出错时获得良好的运行性能。通过采用一种分别在中央控制器和电机驱动器上对反馈信号和控制信号进行补偿的全新延时补偿方法,可以在不增加通信带宽的情况下大大降低通信错误的不利影响。采用了带遗忘因子的递推最小二乘法对由姿态变化引起的时变模型参数进行辨识,并通过在连续丢帧情况下的反馈补偿中引入反向修正率来消除模型误差的不利影响。仿真和实验结果表明提出的容错策略可以有效第减小通信错误引起的系统超调和响应时间变化。
基金financially supported by the Renewable Energy and Hydrogen Projects in National Key Research & Development Program of China (2019YFB1505000)。
文摘An integrated vacuum pressure swing adsorption(VPSA) and Rectisol process is proposed for CO_(2) capture from underground coal gasification(UCG) syngas. A ten-bed VPSA process with silica gel adsorbent is firstly designed to pre-separate and capture 74.57% CO_(2) with a CO_(2) purity of 98.35% from UCG syngas(CH_(4)/CO/CO_(2)/H_(2)/N_(2)= 30.77%/6.15%/44.10%/18.46%/0.52%, mole fraction, from Shaar Lake Mine Field,Xinjiang Province, China) with a feed pressure of 3.5 MPa. Subsequently, the Rectisol process is constructed to furtherly remove and capture the residual CO_(2)remained in light product gas from the VPSA process using cryogenic methanol(233.15 K, 100%(mass)) as absorbent. A final purified gas with CO_(2) concentration lower than 3% and a regenerated CO_(2) product with CO_(2) purity higher than 95% were achieved by using the Rectisol process. Comparisons indicate that the energy consumption is deceased from 2.143 MJ·kg^(-1) of the single Rectisol process to 1.008 MJ·kg^(-1) of the integrated VPSA & Rectisol process, which demonstrated that the deployed VPSA was an energy conservation process for CO_(2) capture from UCG syngas. Additionally, the high-value gas(e.g., CH_(4)) loss can be decreased and the effects of key operating parameters on the process performances were detailed.
文摘In order to improve the design of PSA system for fuel cell hydrogen production,a non-isothermal model of eight-bed PSA hydrogen process with five-component(H_(2)/N_(2)/CH_(4)/CO/CO_(2)=74.59%/0.01%/4.2%/2.5%/18.7%(vol))four-stage pressure equalization was developed in this article.The model adopts a composite adsorption bed of activated carbon and zeolite 5 A.In this article,pressure variation,temperature field and separation performance are stimulated,and also effect of providing purge(PP)differential pressure and the ratio of activated carbon to zeolite 5 A on separation performance in the process of producing industrial hydrogen(CO content in hydrogen is 10μl·L^(-1))and fuel cell hydrogen(CO content is 0.2μl·L^(-1))are compared.The results show that Run 3,when the CO content in hydrogen is 10μl·L^(-1),the hydrogen recovery is 89.8%,and the average flow rate of feed gas is 0.529 mol·s^(-1);When the CO content in hydrogen is 0.2μl·L^(-1),the hydrogen recovery is 85.2%,and the average flow rate of feed gas is 0.43 mol·s^(-1).With the increase of PP differential pressure,hydrogen recovery first increases and then decreases,reaching the maximum when PP differential pressure is 0.263 MPa;With the decrease of the ratio of activated carbon to zeolite 5 A,the hydrogen recovery increases gradually.When the CO content in hydrogen is 0.2μl·L^(-1) the hydrogen recovery increases more obviously,from 83.96%to 86.37%,until the ratio of activated carbon to zeolite 5 A decreases to 1.At the end of PP step,no large amount of CO_(2) in gas or solid phase enters the zeolite 5 A adsorption bed,while when the CO content in hydrogen is 10μl·L^(-1),and the ratio of carbon to zeolite 5 A is less than 1.4,more CO_(2) will enter the zeolite 5 A bed.
文摘Consciousness is the gene of resistance that drives evolution by the evolutionary method-empathic Qualia, the subjective perturbation of “natural selection”, and the choice of which is not limited but stress-resistant to mistakes. Looking into the mirror of ourselves, we bring evolution itself to the mirror, which, without blinking, looks with the eye of a frightened gazelle-incredulously-temptingly. Swinging it with a blow to a blow, taking a lunge and reflecting as the shine of slided comet, translating outrage into joy, the most closed resonant system-consciousness works. It is important not to miss any “punch”(knock/sound/word) that is thrown into your consciousness, so that the sound of the universe (and it is she who sends impulses of understanding) turns into improvisation of your own thinking-becoming a landing from “personal Idaho state”, so that the “muscles” of consciousness pumping iron-training do not sleep like a big earthworm that digested fast food (alimentary, cultured), being content with very little and chafing to empty, in order to work, interpreting what is happening near and around you, and comprehend creatively. The cohesion of eidos is so great that thought literally gains weight-you not only get tired quickly in the process of any “thinking”, but you feel that literally the world with weights hangs in your pockets, throwing a couple of blocks with houses and household on your shoulders. And this is all a consequence of the cohesion and microcoupling of all perceptions that revolve in your mind, touching them democratically: with fluids, resonating with waves of meanings, retransmitting impulses of images, and swaddling with the resulting introjections as by current-already according to Maxwell. Let us leave the God of God, art-skillful, and consciousness-seesaw swing of meanings.
文摘In 2022,the role of digital economy as a stabilizer and accelerator of the national economy was more prominent.Industry digitalization,which is driven by China’ s intelligent manufacturing,has become the main engine of China’ s digital economy development.As the core component of industrial digitalization,industrial e-commerce also developed in full swing.In the past three years,the COVID-19 pandemic has brought plenty of pressure to China’s industrial economy.